Even before opening day this year, St. Louis was hit hard by season-ending injuries to longtime ace Chris Carpenter, closer Jason Motte and shortstop Rafael Furcal. As the summer wore on, the setbacks kept coming.

But the Cardinals kept dipping into the minors for replacements who did more than their share for a team that’s back in the World Series for the fourth time in 10 years.

The kids they plugged in, most by necessity, weren’t wide-eyed at all. They remembered the teaching and just let their ability flow.

“There’s definitely nerves that are going on,” 22-year-old pitcher Michael Wacha said after beating Dodgers ace Clayton Kershaw twice in the NL championship series. “You’ve just got to be able to control them and try to use them to your advantage out there.

“Just not let the moment get too big, just take deep breaths.”

The Cardinals are in the postseason for the 10th time in 14 years. Fresh off their 19th pennant, they’ll go for their second championship in three years when they open the World Series against the Boston Red Sox on Wednesday night at Fenway Park.

Since new ownership took over from Anheuser-Busch in 1996, only the Yankees have more playoff victories than St. Louis.

The pitching staff is deep, thanks to the farm system.

Shelby Miller had a 3.06 ERA this season and led major league rookies with 15 wins. Yet when the playoffs rolled around, there was no room for him in the rotation.

None of them shake off catcher Yadier Molina, himself a product of The Cardinal Way.

“The minor leagues, they’re doing a good job teaching them how to pitch, teaching them how to control the emotions,” Molina said. “Whenever they move up here, they’re ready. Mentally, they’re ready from the get-go.”

No doubt, they’ve gotten a little lucky, too.

General manager John Mozeliak appreciates the organization-wide recognition, but couldn’t have predicted most of the prospects would come through this quickly. Wacha’s sudden dominance is a pleasant surprise, and the same goes for Rosenthal and fill-in first baseman Matt Adams.

John Gast arrived with zero expectations and won his first two career starts. Tyler Lyons, hardly a name on the tip of any fan’s tongue, won his first two starts as well.

“None of that would have seemed right. Right?” Mozeliak said. “Our expectations were not for them to have so many fingerprints on this club.

“It’s a great commentary on the organization.”

Most of the World Series roster is homegrown, a strategy emphasizing scouting expertise and consistency in instruction that allows the Cardinals to keep running with the big spenders.

When longtime slugger and franchise icon Albert Pujols left following the 2011 title for a $240 million contract with the Angels, Allen Craig stepped in at first base and blossomed into a big RBI guy at a fraction of the price.

When Craig went down with a sprained foot in early September, Adams supplied power during the stretch drive.

Sure, the Cardinals aren’t the only team surrounding a highly paid nucleus with products from the farm system. They’re just one of the best at it.

“Even in lean years, these guys find a way to be there,” Texas Rangers manager Ron Washington said this summer. “It doesn’t matter the personnel, this is what’s expected, and they find a way to get it done.”

During his 16 seasons in St. Louis, manager Tony La Russa regularly paid homage to those who laid the foundation. There’s a plaque honoring the late George Kissell, a minor league instructor who schooled Joe Torre in the 1970s on a position move from catcher to third base, and duplicated that with Todd Zeile in the mid-90s.

Second-year manager Mike Matheny came up through the Milwaukee system. He blossomed into a four-time Gold Glove catcher with the Cardinals, and that helped land him the job as La Russa’s successor without managing a game in the minors.

Matheny said he’s just part of the package.

“We’re very, very proud of what our development system, our scouts have done to choose the right kind of guys that can handle coming up here at a young age without a lot of experience,” Matheny said. “Our coaches and roving staff prepares these guys to come up and not be overwhelmed, but be ready.”

Leadoff man Matt Carpenter led the majors in hits, runs and doubles this season. He also was a quick study defensively in transitioning to an opening at second base.

Slick-fielding shortstop Pete Kozma hasn’t let offensive woes bother him on defense, where he’s shined all season. Shane Robinson came off the bench to add a spark in the NLCS.

Wacha sped through the same system, making it to the majors less than a year after getting drafted in the first round out of Texas A&M. Just like the rest of them, he showed up playoff-ready.

“Without those guys, we wouldn’t be where we are,” chairman Bill DeWitt Jr said. “We wouldn’t have won 97 games, we wouldn’t have beaten Pittsburgh, we wouldn’t have beaten Los Angeles. It’s a great feeling.”